a division of Genz Benz Enclosures, Inc.
7811 E. Pierce St. ¡ Scottsdale, AZ 85257
Ph: 480.941.0705 Fax: 480.946.2412
www.genzbenz.com
WARRANTY
Real Tube Direct is warranted for a period of THREE FULL YEARS against
defects to the original, registered owner provided he/she has returned a
completely filled-out OWNER'S REGISTRATION CARD.
This warranty covers parts and labor only; shipping charges remain the sole
responsibility of the owner.
Damage due to modification or abuse is excluded from this warranty.
Before returning any unit for service, a RETURN MERCHANDISE
AUTHORIZATION NUMBER (RMA#) must be obtained by calling
480-941-0705.
4001/4002
Direct Box
OWNER’S MANUAL
We thank you for your purchase of the most innovative direct
box on the market. B.K. Butler’s proprietary circuitry patented.
This is the first known tube cathode balanced direct box ever
designed.
This break-through design results in the elimination of the typi-
cal output transformer. The elimination of the distortion-prone
and frequency response-limiting output transformer coupled
with the addition of a low-noise comparator-type input amplifier
has resulted in a literal order of magnitude advance in perform-
ance for this studio quality device.
While using the RTD, you will notice the almost total lack of mi-
crophonics along with one of the lowest noise floors in the in-
dustry for tube-type studio gear. The noise parameter was
very carefully considered in the design phase.
WHY USE A DIRECT BOX?
The output impedance from your instrument (guitar, bass, etc.) is tradition-
ally quite high impedance. This means that a relatively small electrical dis-
turbance (hum and static from fluorescent lights, or proximity to power AC
lines, for example) can sometimes get into your signal line and then be
amplified along with the good musical signal you want. Additionally, high
impedance is prone to capacitive losses in the guitar cord itself, reducing
the high-end response of your instrument.
The RTD will convert your instrument's high impedance output to a very
low (less than 100 ohms) output. This output can then be sent through a
much longer cable (50 feet is not uncommon) without any additional hum
pick-up or high end losses. Your instrument will be noticeably brighter and
actually more "direct" sounding. Conversion to low impedance makes the
musical electrical signal virtually immune from outside interference.
In addition to providing low impedance output, your RTD also converts
your single-ended (2-wire) instrument signal into a professional true bal-
anced (3-wire) microphone level send for direct connection to the micro-
phone input of a mixing console.
The above-mentioned functions of the RTD are pretty typical of most gar-
den-variety direct Boxes. What is not typical of the RTD vs. other typical
direct boxes is the incredible REAL TUBE tonal enhancement the RTD
gives your instrument!! All outputs are direct "Class A” tube. Be fore-
warned: after experiencing the RTD, other direct boxes will fail to satisfy.
SPECIFICATIONS
Input Voltage Range ….…………………………………. 0 to 3.8 Volts RMS
(45 Volts max. In "SPEAKER” mode)
Max. Output Voltage (Unity) …....................………………... 3.8 Volts RMS
(Normal, Balanced) .. .......………….. 0.5 Volts/phase ref. to pin 1
(1.0 Volts, differential)
Output Impedance ……………………………….Line & Balanced: 100 ohms
(Usually 65 is best)
Signal/Noise Ratio …………………………………………...Better than 90dB
Hum & Noise ……………...……….Better than -75dB (unweighted, no load)
Distortion (THD) ................…………….…....Less than .05% (usually .oq%)
Liberal depends on weighting
Frequency Response .......….………...….15 Hz - 50,000 KHz (+/- 0.25dB)
x unheard of tenth 20-40 flat tenth of a dB
Power Requirement ...............…………………. 30 VAC, 600mA (External)
Tube Complement ...………...12AX7A (selected and each section marked
FEATURES
BOOST/NORMAL SWITCH — Boosts BALANCED output from -24dB to -
12dB (differentially NORMAL measured) below input level Selection de-
pends on the SWITCH sensitivity of the mixing board being connected to as
well as its SIN ratio characteristics. You need to experiment with this switch
set in either position and then adjust the mixer's input pad for the best SIN
ratio and headroom (or clipping limit). NOTE: This switch DOES NOT affect
the 1/4" OUTPUT jack level. The OUTPUT jacks is ALWAYS at unity gain
level (same level as INPUT).
LIFT/ GROUND SWITCH — Lifts and isolates the DC common ground
(input and case ground) from pin 1 of the BALANCED output connector.
Select the position which results in the least hum.
POWER/ON SWITCH — Supplies power to internal circuits. The green LED
indicates SWITCH power "on".
SPEAKER/ NORMAL — Used to select normal (instrument input) mode or
create a line or mic-level send from the speaker output of an instrument am-
plifier. To use in speaker mode: Plug output from amplifier to INPUT jack.
Set switch to "SPEAKER". Plug speaker into SPEAKER/LOOP OUT jack.
Signal available at the OUTPUT jack and the BALANCED will be an isolated
signal with a smooth high frequency roll-off to compensate for the typical
boost that is built into amplifier and is necessary for instrument speakers.
This set up allows you to get the entire sound of your instrument plus your
amplifier into the output of the RTD.
SIDE PANELS (left to right)
INPUT — Accepts a wide range of instrument to line level inputs. Input im-
pedance is 1 Meg. Ohm. NOTE: Be sure "Speaker/Normal" switch is set to
Normal position when using instrument inputs. Use Speaker position only
when connecting to an amplifier's output. (See information under previous
heading "SPEAKER/NORMAL”).
SPEAKER/LOOP OUT — Simply a hard-wired signal loop out which is iden-
tical to the signal fed into the INPUT jack. Connects to speaker (when RTD
is used with an amplifier in "speaker" mode).
OUTPUT — Unity-gain Real Tube Direct output. Typically this jack would be
connected to your combo amplifier's input jack.
TRUE BALANCED — True balanced type output for typical connection to a
microphone on a level input on a mixing console.
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